High efficiency dye-sensitized photovoltaic conversion elements including an oxide semiconductor film electrode sensitized with a complex of a metal such as ruthenium or an organic dye, and a redox electrolyte have been reported. An application of such an element to photoelectrochemical solar cells is now attractive because of high photovoltaic conversion efficiency thereof and capability of manufacture thereof at a low cost.
Organic dyes which have been hitherto used as a sensitizing dye in dye-sensitized photoelectrochemical solar cell include a phenylxanthene dye, a phthalocyanine dye, a coumarin dye, a cyanine dye, porphyrin dye, an azo dye and a proflavine dye. While these organic dyes have a larger absorbance and cheaper as compared with metal complexes and are advantageous as a photosensitizer for reasons of capability of controlling absorption characteristics due to their diversity in structure, the wavelength of light absorbed by these dyes is limited to a relatively short wavelength region so that solar energy transfer efficiency thereof is much lower than that of metal complex such as a ruthenium complex.
It is an object of the present invention to provide a semiconductor film electrode using a specific organic dye sensitizer, a high efficiency dye-sensitized photovoltaic conversion element using the electrode, and a dye-sensitized photoelectrochemical solar cell using the element.